Method of making joints between noncircular tubular members having corners



Aug. 30, 1949. w. R. 0ST 2,480,598

METHOD OF MAKING JOINTS BETWEEN NONC ULAR TUBULAR MEMBERS HAVI CORNER Original Filed Jan. 1944 l IIIIIIIIIIIII INVEN'I'OR willdlm R. 04%. M M

HIS ATTORNEY Patented Aug. 30, 1949 METHOD OF MAKING JOINTS BETWEEN NONCIRCULAR TUBULAR MEMBERS HAV- ING CORNERS William R. st, Verona, N. J., assignor, by mesne assignments, to Walworth Company, New York, N. Y., a corporation of Massachusetts Original application January 25, 1944, Serial No.

Divided and this application October 13, 1945, Serial No. 622,168

8 Claims.

This invention relates to methods of making joints for tubular members and more particularly, the invention resides in permanently connecting the adjacent ends of conduits of rectangular cross-section where a substantially continuous interior surface free from gaps, projections or other interruptions is required. This application is a division of my copending application Serial No. 519,618 filed January 25, 1944, now Patent 2,448,907, issued September 7, 1948.

An object of this invention is to join the adjacent ends of tubular members so that a smooth continuous inner surface results.

Another object of the invention is to hermetically seal the joint between the ends of tubular members forming a continuous length of tubing.

Another object of the invention is to produce a length of tubing from permanently united sections having the characteristics of a unitary structure in performing its intended functions.

Another object of the invention is to utilize the joint element for the tubular members as a holding and aligning device for these members during the joint forming operation. 7

Another object of the invention is to effect permanent jointure between tubular members by simple and economical heating methods which assure production of satisfactory joints without application of skilled welding technique.

Another object of the invention is to secure flanges or other separable coupling elements permanently to tubular members so that no dis- Fig. 4 is a partial perspective view of a modified form of joint.

Referring more particularly to Figs. 1-3 of the drawing. a sleeve Ill of non-ferrous material, such as copper or copper alloy, rectangular in crosssection, is used as the fitting and is provided with an interior surface of uniform bore from end to end rectangular in cross-section and interrupted by a recess I2 substantially equidistant from the ends. The recess H, which is shallow and preferably of rectangular cross-section, extends substantially parallel with the ends of the sleeve around the interior surface thereof and defines connected sockets I4 and I5 therein for the reception of separate tubular members l8 and 20. The sleeve may be of any suitable length to accommodate the entered ends of the tubular members and has a substantially uniform wall thickness from two to three times that of the tubular members. The entered end faces of the tubular members 18 and 29 are positioned in abutting relation within the sleeve I Ii with the recess l2 overlying or spanning the entered ends an approximately equal amount. The tubular members I8 and 29 are of similar rectangular cross-section as the sleeve II] and are preferably a close sliding fit within the sockets I4 and IS with the end faces thereof being smoothly finished and free from fins, burrs or other projections or gaps. 1

Within the recess [2 is an insert of brazin alloy 22 which may be formed from strips of wire pressed into the recess or secured therein by other means including insertion in the molten condition and afterwards set. Preferably, the brazing alloy 22 is a composition of silver, copper and phosphorus, cadmium or zinc or combinations thereof having a melting point of 1050 F. to 1300 R, which is below that of the material of the sleeve l0 and tubular members l8 and 20. The fit between the tubular members I8 and 20 and the sockets I4 and I6, respectively, may be obtained by swaging or other expanding operations conducted on the tubing ends or, if

the tubular members are oversize, by filing or other metal removing process." However, the required fit should be obtained without forcibly driving the sleeve Mon to the tubing end to avoid any distortion of the joint elements.

The inner surface of the sleeve [0 comprising the sockets l4 and I6 is preferably machined to close tolerances as by broaching. The opposed end faces of the tubular members I8 and 20 are also carefully finished to obtain a close fit therebetween when these ends are entered in their respective sockets. In this manner, the tubular members are in alignment and there is no projecting edge or step between the two tubular members at the joint faces. The sleeve I0 thus acts as a holding jig to secure the, desired alignment as well as acting as a container for the brazing alloy.

After the tubing ends have been properly fitted to the sleeve III, the outer surfaces of the tubassesses ing ends are thinly coated with a suitable flux. The flux is not permitted to enter within the tubing ends and any appearing therein is removed. The sockets Id and IE may also be fiuxed prior to insertion of the tubing ends therein. With the assembled parts properly supported against relative movement an oxyacetylene torch flame is applied first to one corner and the two adjacent portions of the surfaces of one tubular member, such as the member l8. The heat so applied to the tubular member l8 adjacent the sleeve I is continued until the flux near the edge of the sleeve l0- begins to bubble. The flame is then directed to the opposite corner of the tubular member l8 and the two surface portions adjacent thereto until a similar condition of the flux is observed. The other two corners and adjacent surface portions are then similarly heated. The purpose of heating the tubular member I8 is to expand it tightly within the sleeve l which remains unheated by the flame during this operation. Distortion of the tubular member during expansion is avoided by the heating method described. It will be apparent that some of the heat applied to the tubular member is transferred to the inside of the sleeve ID upon expansion of the tubular member l8 therein.

After the tubular member 18 has been ex panded the heating of the sleeve I0 is commenced. The torch flame is first directed on to one corner of the sleeve l0 and the portions of the surface oneach side of that corner. The flame is applied with a wiping motion from the middle of the sleeve ID to the edge thereof and on to the tubular member. The corner portion so heated is thus stretched away from the surface of the tubular member I8. The torch flame is then removed in order to permit the heated sleeve portion to unstretch and squeeze out the molten brazing alloy 22 at the corner. Enough heat will have been conveyed into the sleeve ID to bring it to brazing temperature and melt the brazing alloy 22 so that the alloy will flow out from the middle portion toward the sleeve edge.

The flame is then directed on to that corner of the sleeve l0 diagonally opposite the corner previously mentioned. This second corner and the portions of the sleeve adjacent thereto are likewise heated with a wiping motion of the torch from the middle of the sleeve towards the same edge as previously described. The torch is then removed to permit the unstretching operation and appearance of the brazing alloy. The other two corners of the sleeve are then sequentially heated and unstretched as previously described. Completion of the progressive brazing operation to permanently secure the tubular member I8 in the sleeve I die noted by the appearance of a slight fillet of brazing alloy extending completely around the edge of the sleeve adjoining the tubular member when the operation has been satisfactorily conducted. It will be apparent that on larger sizes of sleeves and tubular members the diagonal heating method may be dispensed with and each corner may be heated in sequence by proceeding either clockwise or counter-clockwise around the sleeve or tubular member.

It is an important feature of this invention that the heat is initially applied to the corners of both sleeve and tubular member as distinguished from the surfaces of these members located between the corners. When the dimensions of the sleeve and tubular member are small in comparison with the area covered by the torch flame during the wiping action thereof, it will be unnecessary to separately heat the areas lyin between the corners. However, on larger sizes of sleeves and tubular members it is probable that the intermediate portions of the members between the corners will remain below brazing temperature during the described brazing operation conducted onthe corners. Consequently, it may be necessary to heat these intermediate portions subsequently-to the heating of the corners in order to complete the expansion of the tubular member in the sleeve and also the brazing of the sleeve to the tubular member.

After one end of the sleeve has been completely brazed to the tubular member, a similar series of operations is carried out to secure the tubular member 20 in the socket end i6 oi the sleeve I 0. As the description of this brazing treatment would be repetitive of that previously given herein it is deemed unnecessary to include it in this description.

Upon completion of the brazing operation of both tubular members l8 and 20. the sleeve in is hermetically sealed to the entered ends thereof and a continuous length of tubing may be formed by a similar method applied to other sleeves and tubular members. The brazing alloy 22 penetrates between the abutting ends of the tubular members l8 and 20 during the brazing operation so that the interior surfaces of the tubular members are free from gaps, projections or other interruptions and a smooth interior wall results. In constructions used for conducting high frequency current in certain electrical apparatus, it is highly important that a substantially continuous interior surface be provided and, by use of the teaching of this invention, such products can be quickly and economically formed.

In the embodiment of Fig. 4 a flange 24 is used as the fitting member and is secured to a tubular member 26 by a brazing operation substantially the same as that previously described in connection with the sleeve Ill. The flange 24 which is of non-ferrous material, such as copper or copper alloy, is cylindrical in form and is provided with a reduced neck portion 28 preferably of rectangular cross-section projecting therefrom. The flange and neck portion have a uniform bore 30 of rectangular cross-section. A recess 32 is formed in the bore 30 substantially equidistant from the ends of the flange and neck portion and is preferably located within the boundary of the neck portion 28. The recess 32 is shallow and rectangular in cross-section, as in the previous embodiment, and contains a similar insert of brazing alloy 34 of silver, copper and phosphorus having a melting point of 1050 F. to 1300" F. It will be apparent that the flange 24 could also be rectangular in cross-section if desired or of any other conformation besides cylindrical. Also the neck portion could be cylindrical or otherwise formed as long as the bore is rectangular to receive the tubular member.

The flange connection permits the forming of separable joints between lengths of tubing which may or may not contain permanent joints formed by the sleeve l0. The usual bolt holes 36 may be provided in the flange 24 for connecting it to a similar flange when the length of tubing is made up. The tubular member 26 thus extends through the reduced neck portion 28 and terminates flush with the face of the flange 24 so that an uninterrupted length of tubing may be formed when a similar flange and tubing unit is connected thereto.

The rectangular bore 30 is preferably finished to the'same close tolerances as were used in connection with the sleeve member ID of the previously described embodiment. The flange Parts are accurately finished so that when two flanges are bolted together a continuous, smooth inside surface is present throughout the lengths of tubular members thus connected. Moreover, after the flange is secured to the end of the tubular member 26 no distortion need occur due to the novel heating method now to be described.

The fluxing and brazing operations are con- .ducted on the flange and tubing modification as in the previously described embodiment of the invention. The tubular member 26 is first expanded in the flange bore 30 by heat applied progressively to the four corners and, if necessary,

thereafter to the surfaces between the corners. The torch flame is then transferred to one corner of the neck portion 28 adjacent the junction "with the flange and wiped towards the edge of the neck portion which becomes stretched away from the tubular member 26 and then unstretched vention has been shown and described herein, it

will be apparent that the invention is not limited thereto but is applicable to cylindrical sleeves, flanges and tubular members as well as to the rectangular form disclosed. The appended claims are intended to cover all'modifications which do not depart from the spirit and scope of the invention described and shown herein.

I claim:

1. A method of brazing non-circular tubular members to form a conduit which comprises providing a hollow fitting member having a portion of non-circular cross-section defining a plurality of corners with an. insert of brazing alloy occupying an internal recess therein, introducing a tubular member of complemental cross-section into closely interfitting engagement with the fitting adjacent said insert, applying heat to said tubular member from the exterior thereof first at the corners thereof to expand the entering portion against the interior of said fitting, transferring the application of heat to one exterior corner of said fitting opposite the insert, progressively heating said corner of said fitting from the starting point toward one end thereof to cause a portion of said alloy to melt, withdrawing said heat application from said corner of the fitting to shrink said fitting and cause said alloy to fiow from said recess between said fitting and tubular member, and thereafter sequentially applying and withdrawing heat to a diagonally opposite corner on said fitting to cause another portion of said alloy to melt and flow from said recess between said fitting and tubular member.

2. A method of brazing non-circular tubular members to form a conduit which comprises providing a hollow fitting member having a portion of non-circular cross-section defining a plurality of corners with an insert of brazing alloy occupying an internal recess therein, introducing a tubular member of non-circular cross-section into closely interfitting engagement with the fitting adjacent said insert, applying heat to one outer corner of said tubular member from the exterior thereof to expand the entering portionagainst the related interior corner of said fitting, transferring the application of heat to the diagonally opposite corner of said tubular member to expand the entering portion against the interior of said fitting, transferring the application of heat to one exterior corner of said fitting opposite said insert, progressively heating said corner of said fitting from the starting point toward one end thereof to cause said alloy to melt and to stretch said fitting away from the related corner of said tubular member, discontinuing the heating of said fitting to cause it to unstretch and cause the alloy to flow between said corner of the fitting and the entering portion, and thereafter applying heat as aforesaid to a diagonally opposite comer of said fitting and discontinuing said heating to cause flow of alloy between said diagonally opposite corner of said fitting and the entering portion.

3. A method of brazing tubular members of rectangular cross-section to form a conduit which comprises providing a hollow fitting member having a portion of rectangular cross-section with an insert of brazing alloy occupying an internal recess therein, introducing a tubular member of rectangular cross-section into closely interfitting engagement with the fitting adjacent said insert, applying heat to one outer corner of said tubular member from the exterior thereof to expand the entering portion against the related interior corner of said fitting, transferring the application of heat to the diagonally opposite corner of said tubular member and thereafter progressively to the remaining corners to expand the entering portion against the interior of said fitting, transferring the application of heat to one exterior corner of said fitting opposite said insert, progressively heating said corner of said fitting from the starting point toward one end thereof to cause said alloy to melt and to stretch said fitting away from the related corner of said tubular member, discontinuing the heating of said fitting to cause it to unstretch and cause the alloy to flow between said corner of the fitting and the entering portion, applying heat as aforesaid to a diagonally opposite corner of said fitting and discontinuing said heating to cause fiowof alloy between said diagonally opposite corner of said fitting and the entering portion, and thereafter heating and discontinuing said heating progressively at the remaining corners of said fitting for completing the flow of alloy between said fitting and the entering portion.

4. A method of brazing non-circular tubular members to form a continuous conduit which comprises providing a sleeve member having a non-circular opening defining a plurality of corners with an insert of brazing alloy occupying an internal recess substantially equidistant from its ends, introducing end portions of non-circular tubular members into closely interfitting engagement with opposite ends of the opening of said sleeve member until abutting relation is established adjacent said recess, applying heat to the tubular member first at the corners thereof projecting from one end of the sleeve to expand the entering portion of said tubular member, applying heat to said sleeve from the exterior first at the corners thereof opposite said insert, progressively heating said sleeve from said starting point toward one end thereof to cause said alloy to melt,

withdrawing said heat application from said corners of the said sleeve to shrink the same and cause the alloy to flow in one direction from said recess between said sleeve and one of the tubular members, and thereafter sequentially applying and withdrawing heat to the opposite end of said sleeve first at the corners thereof to cause the alloy to flow in the opposite direction from said recess between said sleeve and the other tubular member, said alloy also penetrating between said abutting ends during the heating operation.

5. A method of brazing non-circular tubular members to form a continuous conduit which comprises providing an annular sleeve member having a non-circular opening defining a plurality of corners with an insert of brazing alloy occupying an internal recess substantially equidistant from its ends, introducing end portions of noncircular tubular members into closely fitting engagement with opposite ends of the opening of said sleeve member until abutting relation is established adjacent said recess, applying heat to the tubular member first at the corners thereof projecting from one end of the sleeve to expand the entering portion against the interior surface of the sleeve, transferring the application of heat to the exterior corners of said sleeve opposite said insert, progressively heating said corners of said sleeve along the portion adjacent said expanded entering portion to cause said alloy to melt and to stretch said sleeve away from said expanded portion, discontinuing the heating of said sleeve to cause it to unstretch and cause the alloy to flow between said sleeve and entering portion up to the margin of said sleeve, and thereafter applying heat as aforesaid to the other tubular member and the opposite end of said sleeve first at the corners thereof and causing the alloy to flow in the opposite direction from said recess between said sleeve and the other tubular member, said alloy also penetrating between said abutting ends during the heating operation.

6. A method of brazing tubular members of rectangular cross-section to form a continuous conduit which comprises providing an annular sleeve member of similar rectangular cross-section with a continuous insert of brazing alloy occupying an internal recess extending around the interior surface of said sleeve substantially equidistant from its ends, introducing end portions of the tubular members into closely interfitting engagement with opposite ends of the sleeve until abutting relation is established adjacent the recess, applying heat to one corner and the adjacent surfaces of one tubular member outside said sleeve, transferring the application of heat to the diagonally opposite corner and the surfaces of the said one tubular member adjacent thereto and thereafter progressively to the remaining corners of said tubular member, said heating being continued until the entering portion of said one member is expanded uniformly against the interior surface of the sleeve, transferring the application of heat to one exterior corner of said sleeve opposite said insert on the exterior thereof, progressively heating said corner of said sleeve from said starting point toward one end thereof to cause said alloy to melt and to stretch said sleeve away from the related corner of said one tubular member, discontinuing said heating of said sleeve to cause it to unstretch and cause the alloy to flow between said corner of the sleeve and the said entering portion, applying heat as aforesaid to a diagonally opposite corner of said sleeve and discontinuing said heating to cause flow of alloy between said diagonally opposite corner of said sleeve and the said entering portion, heating and discontinuing said heating progressively at the remaining corners of said sleeve for completing the flow of alloy between said sleeve and said entering portion of the one tubular member, and thereafter applying heat as aformaid to the other tubular member and the opposite end of the sleeve from the same starting point and causing the alloy to flow in the opposite direction from said recess between said sleeve and the other tubular member, said alloy also penetrating between said abutting ends of both tubular members during the heating operation.

7. A method of brazing a non-circular tubular member having at least one corner portion to a fitting having a complemental opening closely interfltting with the tubular member and containing a brazing alloy insert, comprising expanding the tubular member in the opening by applying heat to the tubular member first at the corner portion thereof, transferring said heat application to the fitting first at the corner thereof to melt the alloy therein, and thereafter withdrawing said heat application to shrink the fitting and cause the alloy to flow between the fitting and tubular member.

8. A method of brazing a non-circular tubular member having a plurality of corners to a fitting having a complemental opening closely interfitting with the tubular member and containing a brazing alloy insert, comprising expanding the tubular member in the opening by applying heat to the tubular member first to the corners thereof, transferring said heat application to the fitting first at the corners thereof to melt the alloy therein, and withdrawing said heat application from the corners of the fitting to shrink the fitting and cause the alloy to flow between the fitting and tubular member.

WILLIAM R. 0ST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

